


The Way Back Home

by TaraxacumClocks (DandelionSea)



Series: Homeward [1]
Category: Underfell - Fandom, Undertale, underswap
Genre: AU, Aftermath of Torture, Alternate Universe - Underfell, Alternate Universe - Underswap, Angst, Experimentation, Hurt/Comfort, If You Squint - Freeform, Medical Experimentation, Medical Torture, Multi, PTSD, Psychological Trauma, Recovery, Torture, Underfell - Freeform, selfcest, underswap - Freeform
Language: English
Status: Completed
Published: 2016-04-15
Updated: 2016-04-20
Packaged: 2018-06-02 09:43:49
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 7
Words: 18,480
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/6561424
Author URL: https://archiveofourown.org/users/DandelionSea/pseuds/TaraxacumClocks
Summary: <blockquote class="userstuff">
              <p>Alphys, the most terrifying monster in the underground, has found a new test subject - a squishy, alternate version of one of her worst enemies, and now it is up to Underfell Sans to save him and get him back where he belongs.</p>
            </blockquote>





	1. Lost and Found

In Underfell, there are three people you learn to fear. First is the great and terrible Papyrus.  His puzzles are dangerous and clever; by the time you notice one, it's far too late.  He practically owns the town of Snowdin, and if one of his canine hunters catches you, you’re going to wish you had died in the cold.

Then there is Undyne - the true Captain of the Royal guard. While Papyrus is loud and boisterous, letting no action go unnoticed, Undyne is reserved and quiet - but by no means less deadly.  She hides in the shadows, eyes always watching your every move, until you finally show your weakness and she strikes with magnificent speed and grace.  Her spear is a herald of death, and the moment it is summoned marks the moment someone dies.

But the one that is truly the one to be most feared is Alphys.  The Royal scientist since long before anyone can remember; it is rumored that she killed her predecessor (and in some versions her whole family) after experimenting on his comatose body. Alphys is neither powerful nor extremely clever, but what she lacks in skill she excels in cruelty.  Monsters that enter her labs do not leave the same, though the lucky ones don't leave at all.  Her basement has never been seen by monster eyes; even the cruelest of the underfallen shudder at the thought of what horrors she has hidden there.

Though, currently, Sans and Papyrus stand at the threshold.

“WELL?” Papyrus snips impatiently. “ARE YOU GOING TO ENTER OR ARE WE GOING TO STAND HERE UNTIL YOUR BONES RATTLE OFF?”

Sans’ strained smile twitches at the comment as he turns to his brother.

“maybe you should go in first? unless the great papyrus is scared?”

Papyrus turns quickly to his brother and Sans flinches, expecting his comment to at least earn him a whack to the head.

“WE DON'T HAVE TIME FOR THIS!” Papyrus yells,  “ALPHYS COULD BE BACK ANY MINUTE.”

Sans rolls his eyes and waves his arms in a grandiose gesture towards the stairs to the basement. “after you, boss.”

Papyrus sighs loudly and grabs his brother by the back of his jacket.  Sans makes a little yipping noise as he is shoved down the stairs, rolling all the way to the landing before landing on his back.  Papyrus puts a hand on the railing, but hesitates to enter.  Papyrus has done many things, but even he is not sure he is ready for what awaits him down below.  “SANS.” he calls out, “WHAT DO YOU SEE?”

Sans is rubbing his head dramatically, but he does look up and around.  “nothin’ much, boss.  just your average sciencey crap.”

Papyrus raises an eyebrow ridge and slowly descends the stairs. He stops at the landing and looks around.  Sure enough there are several Bunsen burners, beakers and other such equipment that is normally seen in a laboratory - but no instruments of torture, nor specimens held tightly to the wall by chains, nor even any such medical equipment that could be used to harm a monster. Papyrus and Sans make their way down a final flights of stairs, continuing to gape at the absolute normalcy of the psychotic scientists basement.

“LOOK AROUND, SANS,” Papyrus says, just a little under his normal volume.  “THAT KOOK MUST HAVE IT HIDDEN AROUND HERE SOMEWHERE.”

Sans gives a little nod and the pair quickly begin pilfering the lab, not even bothering to hide the evidence they were here. After all, what they are looking to obtain will be missed as soon as it is discovered gone.  Hopefully, by then, it would be too late.

Papyrus works his way diligently through the mess of papers and old experiments, fighting a deep rooted urge to straighten up the scientist’s untidy documents.  He is thorough in his search, leaving not a single cabinet, drawer or jar unchecked, so when he turns around to find Sans half asleep on a pile of boxes, it seems only natural for him to throw the small glass container at the wall next to his brother’s head.

“ARE YOU NAPPING? AT A TIME LIKE THIS!?” Papyrus snaps.

“ngh,” Sans’ head jerks up. “naw boss.  i was just tryin’ to think  _ outside the box _ ”

Papyrus slams his fist against the table, making the smaller of the two jump to attention. “I SWEAR TO ASGORE SANS IF YOU DON'T GET OFF YOUR LAZY ASS RIGHT NOW I WILL-”

Papyrus’ threat is cut short by the sound of an automatic door sliding open.  The brothers stand completely still as small, shuffled footsteps sound from upstairs.

“we have to get out of here,” Sans says, getting ready to teleport.

“NOT WITHOUT THE-” Papyrus attempts to whisper are cut off by Sans’ desperate voice.

“do you know what she’ll do to us if she finds us here??” Sans pleads urgently.

Papyrus huffs and rolls his eyes.  “COWARD.”

Before Sans can object (or teleport away, as was his next planned move) Papyrus snatches his wrist and drags him behind the stack of boxes.  Sans lets out a small cry, but Papyrus quickly covers his mouth.

Alphys’ scaly yellow legs can be seen descending the stairs as the pair holds their breath, despite neither of them needing to breathe.  The Royal scientist calmly descends the flight and swivels her head, peering around the room.

“Huh… I could have sworn I heard something…”

Papyrus lets out a silent sigh of relief that Alphys didn't immediately recognize the signs of their break in - though, to be fair, it was a wreck  _ before  _ they got there.

Alphys shrugs and makes her way over to her desk.  She seems to be studying something - some old notes, it looks like. She'll occasionally mark something down, scribbles it out, then marks again.  Slowly, as the adrenaline wears off, the situation becomes extremely boring. Papyrus feels safe enough to let his hand pull from his brother’s mouth.  Sans instantly motions for them to teleport, and Papyrus instantly mouths back ‘not yet.’

“AH HA!!”

Both skeletons jump at the loud cry of enthusiasm, sending two of the precariously perched boxes tumbling to the ground. Alphys pays no mind to the discarded cardboard and quickly rushes to a lab table to mix chemicals.  There is a soft hissing and a dark black liquid oozes into a light red one.  After barely a minute, Aphlys seems to have what she's looking for and rushes over to a cabinet.  Papyrus distinctly remembers looking through that one to only find several dirty lab coats (and one out-of-place dress) but instead of going for the labware, Alphys reaches behind the white fabric and flips some kind of switch.  A wall directly adjacent to Sans and Papyrus slowly begins to creak and a brightly lit extension to the room is relieved.

Huh… So that's where all the disturbing items were hidden.

Sans and Papyrus watch as Alphys enters a room that can only be described as something out of an old horror film.  Dust coats almost every inch of the tiled room - from the shackles hanging from the walls to the knives and saws that had become caked with a solid layer of monster remains.  Sans begins to feel a little dizzy and even Papyrus is left a little wide eyed. Papyrus is a warrior and a leader.  He would not hesitate to put a bone through someone’s head just to prove a point…but this…this is just a bit much.

And in the corner, huddled in a tiny cage, lies a monster.  It's a skeleton, no doubt, but something about its bone structure unsettles the duo, though neither of them knows exactly what is so strange about it.  Maybe it's just the shock of actually seeing another skeleton?  There aren't many out there, besides the bone brothers of course. 

Alphys approaches the cage slowly, seeming to savor each step that draws the curled up monster closer to the fate it fears. It is shaking violently, enough so that the room is now ringing with the sounds of the rattling metal surrounding it.  Alphys stops at the cage, towering over her prisoner with glee.

“Ah, there’s my favorite subject~” Alphys’ voice is so sugar-coated that it almost feels as though real affection lies behind her words. Perhaps, in her mind, it does.

The skeleton makes a small series of noises that seem to be a bastardization of speech. Alphys ignores this and opens the door.  Instead of bolting like Sans and Papyrus thought it would, it simply sits there, pushing itself farther back into the cage.

“Come on, don't be like that,” her voice is still calm and sweet, completely contradictory to the actions that all monsters in the room know are about to take place.

Alphys reaches a hand inside the cage, then two, pulling the little monster out of his only safe place by his shoulder bones. The monster struggles some, though it seems to realize the futility of this and goes limp in mere seconds. In response, Alphys lightly pats his head and gives a small string of praises.  It's one of the most sickening displays either of the onlookers had ever seen.

They watch helplessly as the monster is tied to a table in the center of the room, tight fitting leather straps encircling its wrists. Alphys pulls over a small tray of tools and begins to sort through them, seeming to deliberately take her time in order to torment the monster. It has begun to shake again, and honestly, no one can blame it.  The monster’s defining features have mostly been hidden either by angle or light, so the pair still is at a loss for its age and identity. Sans shifts to get a better view of the creature’s face, though Papyrus pins him down.  Something about that monster is so unsettling to him - well, besides the fact that it is probably about to be consciously vivisected.

“Now, where shall we start today, hmm~?” Alphys’ smile has morphed into a blissful grin as she slowly works her hands down the skeleton’s ribs, carefully navigating the cracks and bruises running down them.  There is no doubt of who is behind all of them.  “I'm going to up the dosage by almost fifty percent, but don't worry - I added in a little something in so you won't die.” She giggles a little. “Probably.”

Alphys steps away from the table and turns her back to the subject, and thus, the brothers.  Papyrus decides enough is enough and grabs Sans by the shoulder, shocking him out of his stupor at the events unfolding before him.  Papyrus motions him up the stairs and Sans complies without a thought.  Teleporting makes a small noise and Alphys would no doubt notice - besides, Sans doesn't want to stick around for whatever happens next.

As he's climbing the stairs behind Papyrus, he can hear Alphys’ ecstatic purring.

“After all,” her voice is flooded with seductive dust-lust as she returns to the monster, needle poised.  The skeleton is thrashing again and Alphy’s deranged giggles are mixed into the pleading whimpers as the needle is mercilessly thrust into its soul.

“You are my most durable subject, aren't you, Sans?”

As Sans teleports himself and his brother away from the nightmare, all that can be heard is the agonized cries of Alphys’ latest victim.


	2. Unintentional Rescuer

**Summary for the Chapter:**

> Sans returns to the basement to continue his search.

**Notes for the Chapter:**

> Wow!! People _really_ liked this fic. Funny thing is, I almost didn't write it because I thought no one would like it. I got about halfway through the second chapter and stopped, but I showed it to my Beta and they pressed me to keep writing. I'm glad they did.

Papyrus paces the living room angrily as Sans reclines on the couch, seemingly on the verge of a nap.

“BAH!  WHAT A WASTE OF MY VALUABLE TIME!” He yells, knocking over yet another lamp in his erratic display.  “NOT ONLY DID WE NOT GET THE SERUM, BUT NOW I AM TOO SICK TO EAT!”

“that's not true, i’m sure you'll find a way to _stomach_ it.”

Papyrus chucks the remote at Sans’ head, and only his quick dodging skills save him from being hit square in the face.

“THIS IS ENTIRELY YOUR FAULT, BONEHEAD!” Papyrus yells.

“my fault?” San snaps, “you're the one too stupid to look behind the lab coats!”

That was a mistake.  Sans curses his loud mouth as Papyrus stomps over to him and grabs at his shirt, missing only by an inch as Sans turns and runs.  Sans rushes behind the couch and throws the cushion at his brother as a distraction before bolting across the house.  Papyrus makes it over to his brother and tackles him to the ground, pinning him there by his shoulders. 

“NOW LISTEN HERE, YOU DISGUSTING EXCUSE FOR A WORM,” Papyrus snarls, pushing his face into Sans’. “SINCE YOU DIDN’T DO ANYTHING LAST TIME, YOU ARE GOING TO RETURN TO THOSE LABS AND GET WHAT I NEED TONIGHT.  ALONE.”

Sans eyes go wide. “b-boss… i c-can’t…”

Papyrus pushes off of Sans and stand at his full height.  “YOU ARE PERFECTLY CAPABLE OF DEFENDING YOURSELF, BROTHER.  IT'S ABOUT TIME I STOPPED BABYING YOU.”

Sans looks as though he wants to object, but the words die on his metaphorical tongue.  Papyrus seems to have made up his mind on this one, and there is no reasoning with him once as he’s done that.

“fine,” Sans huffs, pulling himself to his feet.  “i’ll get your stinkin’ drug.”

“GOOD.” Papyrus says, standing triumphantly with his arms crossed across his chest.  Sans readjusts his coat and stomps up the stairs.  “WHERE DO YOU THINK YOU’RE GOING?”

“to take a nap.” Sans growls. If he’s going to be up all night doing his brother’s dirty work, then he is at least going to be well rested for it.  At least, as well rested as Sans can get.

Before Papyrus can object to his perceived lazy behavior Sans slams the door to his room.  Everything in the room is broken, rotted, filthy or just a mess; It feels like home.  Sans flops down on the mattress with no covers and looks up at the ceiling.  He traces the patterns in the broken wood several times over, trying and failing to forget all that he’s seen.  The screams of the tormented monster still echo in his mind.  Sans wonders about what Alphys has said.  The monster down there was another Sans - another him. God only knows how Al got her hands on a monster from another universe, but there was something deeply disturbing about seeing your alternate self’s soul being ripped out and abused. 

Sans rubs his own soul, phantom pain springing up at the mental image.

The little thing was so broken too.  Sans has seen monsters that made it out of Alphys’ lab before.  There was always something…haunting about them.  Many of them never spoke again, and others were simply too far gone to be called people - reduced to creatures of pain and instinct with less of a mind than an animal. Most of them were killed as soon as they were found, not out of spite or malice, but simply out of pity.  No ex-experiment of Alphys’ ever objected to a mercy killing.

Sans groans at the thought of having to go back there.  He would love nothing more than to just put that nightmare behind him and go to sleep.  The other Sans was probably dust by now anyways, and if he isn’t already, he will be in a few days.  It hadn’t looked like Alphys had been feeding him, after all.

If Sans does see the little guy when he goes back, he will have to kill him.  Sans may have done some questionable things being the brother of Papyrus, but even he couldn’t leave a monster in the hands of the cruel scientist.  Alphys will probably just assume he died in his sleep.

Eventually Sans drifts in and out of consciousness, uneasily setting between dreams of being caught in the lab and being caught in the other Sans’ cage.  When he is finally woken up by his brother’s yelling, he feels even less rested than when he had first laid down.  

Sans slips into his shoes and drags his coat over his shoulders.  With a quick “i’m going” shouted through the door, Sans shortcuts out of the room.

\---

He makes his way through Alphys’ lab without any trouble.  Years ago he was a scientist here, after all, but he quit almost the same time that Alphys started.  Lucky him, he guesses, as there have been several lab assistance who have mysteriously disappeared since then.  Sans shudders to think of what might have happened to him if that loon had gotten her hands on him. 

Probably the same thing that she was doing to the other Sans right now.

Sans quietly looks around for the scientist as he tiptoes through the halls.  His eye sockets eventually rest on her sleeping form, perched on a chair in front of a personal computer.  A very disturbing anime is on screen. It’s frozen on a naked woman who seems to be disemboweling a man with her mind. 

Sans snoops past her and quietly opens the door to the basement.  He doesn’t trust himself to teleport down there on his own after only one time being in the room.  He makes his way down the stairs and to his relief the wall to the horror room is still open.  Sans quickly slips into the place and begins digging in the cabinets, hoping to find what he was looking for as fast as possible so he can get out of here.

There is a small noise on the other end of the room, and Sans turns to find a pair of bright blue eyes peering back at his own red ones.

Shit. He’s still alive.

Looking at the other Sans up close is even worse - especially since Sans now recognizes the figure as himself. The Sans in the cage is missing almost half of one of his hands, and his ribs are cracked in such a way that his soul is completely exposed. His skull has been broken and healed over and over, as evidenced by the multiple thin, white lines.  By all rights he should have died many times over by now but this half-way-to-dust monster is still, somehow, alive.  An appalled shudder makes its way down Sans’ spine; the look of disgust must have shown on his face because the other’s eyes suddenly meet the floor. 

Sans sighs. He had been hoping that he would have found what he needed before doing this, but he really can't leave the little guy to suffer like this.

Sans slowly moves closer to cage, and the other backs away from the door.  He carefully undoes the latch and kneels down at the opening.  Those big blue eyes are full of confusion and wonderment and fear - it’s honestly very exasperating for the emotionally bankrupt counterpart.

“Come here.” Sans orders forcefully, a trait he is mimicking from Papyrus.  This is apparently the wrong thing to do, as the abused skeleton either doesn’t understand, or care what Sans wants him to do.  

Sans blows out a frustrated huff of air.  He reaches into the cage - which, thankfully, isn’t too large - and grabs ahold of the Sans’ wrist.  He jerks back and lets out a loud cry, prompting this world’s Sans to quickly shush him.  The skeleton instantly goes quiet.  Sans is able to get his arms around him better now, careful to avoid the hole in his counterpart’s chest, and pulls him out of his prison.  

Once as he’s on the outside, the Sans simply sits down and looks at his rescuer with a confused expression.

While Alphys’ test subject is trying to process what is happening, Sans quietly summons a bone in his left hand.  He has to do this quickly and quietly - he still needs time to find what he’s looking for, after all. Unfortunately, as soon as the bone is in the sight of the other monster, he panics and scrambles away, a long string of strange noises leaving its mouth.  Sans moves after the little creature as he backs himself into a corner, banging its head against a table loudly.

“hey, come back here.” Sans whispers, tempted to just throw the bone and get it over with.  But that would make far too much noise - if the commotion hasn’t already woken Alphys,  “come on, kid, i’m trying to help ya.”

The smaller Sans doesn’t seem to understand him, as he is still kicking his legs uselessly against the ground, as if he can come how increase the distance between him and Sans by doing so.  The look of lose and desperate fear in his eyes is beginning to annoy Sans.  He didn’t have to help the monster out of his prison. Sans could have easily left this monster to whatever hell Alphys has in store for him.

Sans marches over to the skeleton in the corner, who has given up his futile thrashing in favor of babbling. They are all sound and syllables that Sans recognizes from language, but the sounds are in no way forming coherent words.  It sounds suspiciously like pleading, though.

“you want out, kid?  this is your way out.” Sans says, beginning to become exasperated with the shivering mess on the floor,  “i ain’t tryin’ to be mean, that’s just how it is.”

The blue eyes are boring into his now as the skeleton seems to be trying to understand what Sans is saying. With the skeleton lost in his own thoughts, Sans decides that now is the time and quickly raises the bone back.  He’s dusted a monster in one good swing before, and with one as weak as the one before him, it shouldn’t be too hard.

Just before he releases his arm to swing, Sans registers movement in front of him.  So it seems the little one’s got some fight left in him; Sans braces himself for what he is sure is going to be an attack.  

But instead of a malicious and painful contact, the small skeleton has attached himself to San’s middle.  It takes Sans a few moments to realize that this is an embrace.  Sans just stands there.  He hasn’t hugged, or been hugged, in several years… he’s completely at a loss, frozen in his attack stance.

The other Sans has buried his face into Sans’ jacket and muffled sobs of despair leak through.  He whole body has become a trembling mass of sorrow, and even Sans can’t help but feel some pity - some, mostly disgust and annoyance, though.  Sans let’s his hand drop.

“uh…” The awkwardness of the situation sinks, and Sans is left there holding the shaking bones in the strange pseudo-embrace.  He doesn’t even know if the skeleton  can   understand him, but he tries anyways “look, kid, i… uh… i know you're scared and all…but… uh... i’ll be quick, i promise.  you won’t feel a thing.” The skeleton only burrows further into Sans’ shirt, quaking even more.

 It dawns on Sans that the skeleton still wants to live.  Sans is completely at a loss for how to proceed.  This has never happened before when trying to put a subject out of its misery.  Most would opt to do it themselves if they had enough of a mind left for it.  How could anyone survive Alphys’ lab with their will to live still intact?  

Sans shakes his head.  This Sans can’t even talk anymore, and the partly healed wounds on his body still have to be causing him pain… so how can he  possibly   survive?  Its better that the little thing dies here quietly than out there where there will be monsters who will to tear him to shreds; he’s suffered enough.

The frightened skeleton’s face is burrowed deep into Sans’ chest; he realizes that the monster won’t see it if he summons an attack now.  It’s better that way.  He doesn’t need to know what’s happening.

Sans’ hand rests firmly on the back of the cracked skull, locking the other into place.  Sans is about to create another bone to finish the suffering monster when the sound of a door opening fills the room.

“Who’s there?” Alphys’ voice rings out.  Underneath the anger this is a small bit of excitement in her voice that chills Sans to the bone.  “I know you’re in here!”

Sans instantly grabs the other Sans around the middle, causing him to gasp quietly, and quickly teleports out of the lab.  It takes a few jumps, but finally Sans is at the edge of Snowdin forest and he finally feels safe.

Until he realizes that he’s just returned empty handed.

And with one other passenger.

“shit!” Sans kicks the snow around him violently.  “motherfucker!” 

The blue-eyed sans shrink down at the loud voice and whimpers loudly.  Sans is tempted to blast the little shit out of existence right then and there… but as soon as Sans raises his hand the little monster yelps and scrambles around in the snow.  It looks as though he's attempting to get to his feet, but he only ends up face first in the snow.  The display is so absolutely pathetic it’s funny, and maybe it’s the stress or relief of the whole ordeal, but Sans cannot help but laugh at the tiny thing.

He only stops when the other Sans starts laughing too.

“what’d  you   have to laugh about?” Sans snaps,  “i’m still gonna kill ya.”

 

The mirth fades from those blue eyes as Sans begins to summon an attack.  Realizing what is about to happen, the smaller monster begins scrambling to find his magic to defend himself, but through his hunger and exhaustion only tiny, harmless blue sparks appear.  Sans smirks at the display and begins to approach, only to feel something wet and cold hit his face.

He stops and presses a hand to the impact, pulling it back to find clumps of snow stuck to his glove.  He is hit again and this time he sees the Sans he rescued balling up his next attack.

“snowballs?” Sans deadpans,  “really?  you’re that desperate?”

He throws another one and Sans quickly blocks it before it can hit his face.  The Sans on the ground looks at him with a resolute and defiant look.  Sans finally throws his hands up in the air.

“you wanna live so bad, fine, ” Sans says, trudging off,  “i don’t even care anymore.”

Hands shoved deeply in his pockets, Sans kicks the snow as he makes his way back home. What the hell is he going to tell Papyrus?  The fact that he hadn’t gotten what he gone there for was one thing, but now Alphys knows that he was there.  Well, she knows someone was there, and there is a good possibility that she will be able to guess who.

Getting his hands on liquid determination will be next to impossible now.   The only other place it can be found outside of the lab it was created in would be in Asgore’s castle, but like hell either of the skeleton brothers would be able to get it from him.

Papyrus is going to be pissed.

Sans kicks another snow poof into snowy dust and lets out another string of curses.  It is only after he calms down some that he notices he is being followed.

“go away, kid.” Sans snaps at the little skeleton behind him, “don’t you have someone else’s life to ruin?”

The little Sans is shaking, but this time from cold, not fear.  If he had clothes to begin with, Alphys had taken them, and walking around Snowdin forest naked typically isn’t the smartest thing to do.  He is giving the other Sans a desperate, pleading look.

“cold?” Sans sneers, “that’s your problem.”

He turns away and walks another couple feet, but when the footsteps don’t stop he swings around again.

“i’m serious, kid,” Sans yells.  “take one more step in my direction and there ain’t gonna be enough dust left for a funeral!”

The other Sans takes a step back and falters, falling onto his back.  Sans is about to say something to him when he notices the other’s eyes are closed.  Sans slowly approaches and kneels beside his counterpart. He’s out cold.

Sans looks down at the skeleton in the snow.  If he walks away and leaves him like this, his counterpart will freeze to death.  Not the worst way to go, especially since he was already knocked out.  Sans has certainly seen worse, much more gruesome deaths in his lifetime.  The most sensible thing to do now is leave the little creature to die on his own in the snow.

But that look in those blue eyes that had mirrored Sans’ own red… this Sans never stopped fighting, even when he knew it was hopeless.  After all the little thing has been through, he still wants to live.   

Sans curses himself and his inner compassion as he lifts the tiny version of himself over his shoulders.  The Sans doesn’t even shift, lying as totally dead weight on the other.  With that, Sans lets reality shift and ends up surrounded by familiar white walls.  

Depositing the skeleton carelessly in his lab, Sans reluctantly goes off to meet with his brother.

**Notes for the Chapter:**

> Headcanon: Underfell Alphys _loves_ dark animes like Tokyo Ghoul, Deadman Wonderland, Parasyte, Higurashi, Corpse Party, Rabbit Doubt... The one she's watching here is Elfen Lied.


	3. Wake Up

**Summary for the Chapter:**

> Other Sans wakes up in another lab, and is none too please.

“HOW!?  HOW, SANS!?  HOW DO YOU FUCK UP  _ THIS  _ BADLY??”

Sans sits on the couch, nursing a swollen cheek bone from where Papyrus had nailed him when he got the news.

“alphys doesn’t exactly lable her shit, paps,” Sans says.  Papyrus swings at him again, and even dodging Sans still gets nicked in the side of the head.  

“CALL ME THAT AGAIN, I DARE YOU!”

Sans snarls at his younger brother and he’s tempted to say it again, just to spite him, but even Sans knows he’s already in too much trouble as it is - and he _really_ doesn't want to deal with broken bones on top of everything else.  So Sans elects to simply glares at the taller skeleton and stands.

“whatever,” he mumbles.  “i’m going to grillby’s”

“YOU MOST CERTAINLY WILL NOT!” Papyrus yells.  “YOU ARE TO STAY HERE WHILE I CLEAN UP YOUR MESS.   _ AGAIN _ .”  Papyrus pushes past Sans and heads for the door.  “AND IF I FIND OUT YOU LEFT THIS HOUSE I WILL LOCK YOU IN THE SHED OVERNIGHT.”

With that, Papyrus slams the door and stomps away.  Only after Sans can no longer hear his brother's enraged mumbling does he finally let out a breath and relax.  He flops down on the couch and leans back. 

When Sans had told his brother that he didn’t have the determination, Papyrus was pretty upset (enough to give Sans a bruise that’ll last a while) but, all things considered, he took it rather well.  Sans has been hurt much worse for much less when he catches Papyrus on a bad day.  He's surprised it didn't turn out worse for him.  Then again, he  _ did  _ leave out a pretty big detail…

Speaking of the little skeleton - Sans stands up and stretches.  He runs to his room for a minute to grab some things then makes his way out of the house and to the tool shed, which his brother has recently converted into a human holding cell/ torture chamber, and grabs the small dog bed and blankets they kept there.  He then strolls out and makes his way behind the house.

He still doesn’t know what he’s doing, keeping the alternate version of himself locked up in the lab.  Sans still thinks that he should have killed the brat, but at the same time he really admires the guy.  He made it through Alphys’ lab, after all - not bad for a Sans.

Sans unlocks the door and immediately wishes he’d left the little fucker out in the snow.

His lab has been torn up and Sans is nowhere in sight.  Swearing lightly, Sans drops the blankets and takes inventory.  It’s mostly superficial damage - papers on the ground, broken glasses, a knocked over table - it looks more like he had panicked than deliberately trashed the lab.

Which sounds  _ extremely  _ likely now that Sans thinks about it.  

But the real question now is where the little guy had ended up.  Sans pushes through the discarded papers and trash, trying to track the movements of the past hour.  It seems the skeleton woke up and instantly made a break for an exit, only he didn’t exactly  _ know _ where the exit was, so he just kept running into walls.  Sans knows that he never made it out of the room because for one, the door was still locked, and two, if the other Sans could teleport there would have been nothing stopping him from doing it earlier. 

Still, the skeleton is nowhere to be found, and it could take  _ hours  _ to coax him out of hiding.  Sans lets out a frustrated grunt and kicks a wall.  He is about to let loose a long list of swears when he hears a small whimper coming from inside one of his cabinets.

Smiling wickedly, Sans paces over to small space under his lab desk and opens the door.  Sure enough, there is a tiny, shaking skeleton hiding there, head tucked into his knees.

“alright, alright,” Sans says, a small bit of amusement breaking into his voice at the other’s discomfort.  “i get it.  dropping you off at the lab after being with al for so long wasn’t the brightest idea.”  The smaller Sans either doesn't understand or doesn’t hear, too absorbed in his terror to respond.  Sans is quickly losing patience again.  “fun's over, get out.”

Sans is beginning to think that his little rescuee can no longer understand simple speech when slowly the little skeleton shakes his head.

“no?  you’re not coming out?”

He shakes his head again.  Sans huffs in annoyance and rolls his eyes.

Sans quickly turns the skeleton’s soul blue and drags him out of the tiny cupboard.  The other Sans lets out a small squeak and attempts to scramble out of Sans’ magical grasp.

“stop that!  i’m not going to hurt you.” He grunts finally grabbing the other Sans’ arm.  That was a mistake, as the instant his boney fingers met the other’s arm he panics and screams.  The  shriek is enough to momentarily distract Sans, hands instinctively going up to protect his ears, despite lacking them.  With his soul suddenly free, the other Sans makes a run for it.  Unfortunately, with nowhere to go, he hits a wall almost the second he started.  By then, Sans has recovered and is facing the skeleton, who had pressed his back defensively against the wall.

“what is wrong with you?” Sans snaps.  The little skeleton simply continues to shake, watching him like prey watches predator.  Sans huffs in annoyance.  “i should have left you out in the fucking snow,” he grumbles.

Sans once again begins to approach his captive, but as the skeleton presses his back further into the wall away from him, Sans gives up and turns around.  He has more important things to do than console his unintentional charge.  

Confused, but ultimately pacified, the other Sans sits down and watches.

Sans begins looking through his old documents.  He makes a small attempt to clean up the mess the other had made, but he barely manages to start before he gets tired of it and moves on.  He waded through old theories and equations that were so easy to him at one point, but after almost a decade of absence they're just as unfamiliar as they were at the beginning.

The other Sans, calmed now and somewhat curious, comes up behind him.  Sans doesn't notice him at all as he is rereading the same sentence for the fourth time in a row.  He can't believe that he wrote all this stuff;  The equations alone look like another language even though it's written in common!  Frustrated, he attempts to storm off, only to run straight into his other self.

“agh!” Sans jumps back, ready for an attack.  His magic is pulsing fast, ready for the draw, but when he recognizes the other skeleton he quickly pushes it down, taking deep breaths.  When he’s calm, he glares down at the little skeleton.  “do we need to put a bell on you?”

To his absolute shock, the other Sans shrugs.  Sans rolls his eyes and pads over to the dropped pile of blankets.   “speaking of putting something on you,” Sans says, reaching into the pile. “here.”   Sans tosses an old, torn up jacket and a pair of thick pants at the skeleton.  He doesn't catch it, but he does pick it up and examine it.  For a frighteningly long minuet it looks like he doesn't recognize what the items in his hands are, and Sans begins to think he's going to have to dress the little fucker…

But he slips a hand through the sleeve hole and slowly zips the jacket up.

Sans smirks.  It's almost like looking in a mirror, except a little more beaten up with scars in the wrong places and a real tooth in place of his fake.  And of course there's the eyes, but honestly, his blue eyes stand out better against the faded red and brown of the jacket.  

When he's fully dressed, Sans gives an approving nod.  “not bad, blue,” he says.  “in that you  _ almost _ look like a real monster.”

The skeleton gives him a confused look, and Sans gives up trying to communicate with the selectively brain dead monster.  Although, thankfully, It's beginning to look like the instability in his comprehension is entirely mental rather than physical.  The injuries are bad, but thanks to monster food and magic, they should be manageable for Sans alone - at the very least not life threatening.  That's definitely a plus, because if the monster needs a real doctor he'd be shit out of luck.  Doctors are few and far between, and only treat the most important monsters in the underground.  At least the jacket covers the exposed hole in his chest leading to his soul.  Sans doubts there's a way to fix that.

Sans returns to his table, and, deciding that there isn't anything else he can learn from just the blueprints alone, makes his way to the machine.  Actually looking at the thing after so long of it just collecting dust is almost nostalgic.  

Ripping through the wires he makes his way directed to the core of the machine.  The power source is still running after all these years, though it's going to need an electrical start if Sans wants to get things running smoothly.  He just hopes that Papyrus doesn't notice the bill.

Suddenly there is a large crash from behind him.  Sans jumps and spins on his heals, growling in frustration as he find the blue eyed monsters standing beside a knocked over shelf.

“the hell you think you're doing?!”  Sans shouts at him.  The loud tone is enough to scare the skeleton just short of panicking.  Sans growls, this time in frustration.   _ Anything  _ can set his guy off; It is honestly like working with a spoiled child.  Except when he looks back the skeleton is once again trying to summon his magic to protect himself, only failing due to fatigue.

“i already told ya i ain’t gonna hurt you,” Sans snaps.  “i wouldn't be wasting my time trying to get you back home if i was.”

The little skeleton seems to calm a little, though his magic is still flaring blue - same color as his eyes.

Sans gets a little closer, and the skeleton  _ really _ doesn't like that, as the blue sparks start increasing.  Sans grabs his wrists in one hand and forces them down.  The other skeleton’s magic finally stops, not because he’s calmed but because he simply cannot manage it anymore.  The other Sans’ eyes are wide and scared, refusing to meet his counterpart.

Sans’ face is inches away from the other when he growls, “no.”

The other Sans instantly goes slack and Sans let’s him go.  He crumples to the floor and sits there, looking defeated and pathetic.  It frustrate Sans to no end to watch a monster who shares his place in the universe be so utterly useless.  If Sans was anything like this, Papyrus would have killed him a long time ago.  Hell, if Sans keeps messing up, he might just anyways.

It takes a full minute for Sans to realize that the blue Sans has collapsed from hunger.  Sans swears lightly and takes a quick shortcut to the kitchen.  Old leftover pasta is all that's in the fridge, but it should do the trick.  Sans returns to the basement and nudges his semiconscious counterpart.

“wake up, lazyass,” Sans says, pushing the food in the skeleton’s direction.  He lazily opens his eyes, glancing hazily at the food before bolting up and grabbing at it.  Sans is sloppy and a general mess, but even he is a little disgusted at the way his counterpart is shoving the food in his mouth.  Sans shrugs it off though - who knows how long it’s been since the little guy ate?

Getting back to work Sans spends the next few hours tinkering with the machine.  A twist here, a pull there - slowly he is beginning to get his bearings in his creation again.  After a while though, Sans’ stamina wears out.  Rubbing his eyes, Sans puts down his tools and turns around to see the little skeleton fast a sleep on the pile of blankets he had brought.  Sans smirks and strolls over to the unconscious skeleton.  Like this he could almost be called cute, if cute wasn’t a word that got people killed around here…

“‘night, blue,” Sans says.  He strolls out of the lab and up the stairs, flicking all but one of the lights off as he goes.

When Sans settles down in his bed, he feels the closest he’s felt to happy in a long time.  Ever since Papyrus joined the Royal Guard, Sans hasn’t had time to work on his projects.  Besides lack of funds, parts and general motivation, Sans has also had to keep up appearances as a sentry so his brother wouldn’t hassle him over making him look weak.  It wasn’t the worst life, but it certainly isn’t the one Sans would have picked for himself.  With this new mystery on his hands, though, he actually finds the jumpstart he needs to pick his work up again.

There are so many questions about the Blue Sans.  How did he get here?  How long has he been here?  How long has he been with Alphys?  It would be so much easier if Sans could just ask but it seems the little guy is going to be clammed up for a while.

Sans sighs, one step at a time.  Step one is to get the machine operational for interdimensional travel.  That alone is going to take up a large portion of time, and hiding Blue from his brother is going to be no easy feat. 

Sans eyes slowly close.  Tomorrow.  These are all problems for tomorrow.  Finally drifting off, Sans slips into a dreamless sleep.

 

**Notes for the Chapter:**

> Enjoying so far? I hope so!


	4. Mistakes are Made

**Summary for the Chapter:**

> Sans makes a mistake that makes life difficult for the pair.

**Notes for the Chapter:**

> Surprise chapter~!
> 
> I'm uploading this tonight because I'm just finishing up the next chapter (yes, the fic _is_ finished, I just added in the chapter after this one because of a helpful comment I got) and I needed to reread and edit this one. I will be done by tomorrow so it can be uploaded on time, but it will be super short. 
> 
> Therefore, BONUS CHAPTER!!!

It takes several weeks just for Sans to get the lights on.  Granted, he can only work on it at night and on his ever-so-rare off days.  Those weeks consist mostly of Sans re-teaching himself all that he’s learned about quantum and regular mechanics, but after he's retaught himself the basics things start to go more smoothly.  Hopefully the most eclecticity draining parts were over with now that the power core is stabilized - Papyrus was  _ not _ happy with the bill.  Sans is working at a steady pace now, and if all goes well he should have the damned thing running by the end of the month.

Of course, Sans is never alone in the lab.

“blue,” Sans calls lightly as he enters the lab.  “brought dinner.”

A little head pops up from out of the pile of blankets and an eager little Blue rushes over to him.  Over the past few weeks Blue, as Sans has dubbed the alternate version of himself, has become far more comfortable, even if he has still yet to say a word.  At first, he would stay in the corner, barely making any noise.  Sans didn’t mind that at all, but then Blue started getting curious and looking over his shoulder.  Slowly, the skeleton would start to point to things, silently asking what they were.  Sans would sometimes explain, but most of the time he would just ignore him or tell him to go away.  Blue is also, as Sans found out, very judgmental. Many times Sans would bring down a bottle of mustard to help with the stress, and every time Blue gave him a very disapproving look.  Sheesh, he thought he could at least get a break from  _himself_ of all people...

Still, as annoying as he got, Sans much prefers the calm and curious Blue to the shivering weakling he’d first brought here.

Sans pops the lid off the small take out box he’d brought home from hotland.  Papyrus had been getting suspicious of Sans’ new “eating habits”.  The food Sans had been sneaking off to his little guest hadn’t apparently been going unnoticed.  This lead to a very uncomfortable and near-violent conversation in which Papyrus had asked if Sans was pregnant.  Since then Sans has been trying to avoid bringing food out of the house for Blue.

Blue eagerly accepts the offered food and wolfs it down.  His manners have improved only slightly, so now he looks more like he’s just a natural messy eater than starved.  Though, to be fair, he always cleans up after himself.  Blue never leaves a mess and even his little bundle of sheets is kept neatly in his corner.  He has a cleanliness computation that could rival Papyrus’, often seeming to get upset when Sans leaves papers lying around.

Blue looks up at Sans and points to his papers then the machine, silently asking what he's going to do today.  Sans smiles and motions to the machine.  Blue nods and goes back to his food.

This is definitely one of Blue's good days.  On good days Blue is engaging, listening, and sometimes even hyper - but on the bad days he can just stare at a wall for hours, completely still.  He doesn't make a sound or move a muscle, but when Sans puts food in front of him he'll force himself to eat without guto or joy - almost like a zombie.  It's entirely unnerving and Sans wonders what goes through his mind during those days.  Not that he'd ever  _really_ want to know...  Thankfully, as the weeks went by, the depressive episodes became fewer and shorter - going from four a week, to two, to one, to having gone almost a full week without problem.

Sans watches Blue for a minute then heads over to the machine.  A week ago he got the power working on all parts of the machine, now he just has to find a way to sync it up with the quantum signature unique to his universe.  Once as he has that, he can create a tear in spacetime large enough to push the machine through yet small enough not to plunge the whole world into the void.  It’s honestly quite exciting for Sans - playing with the fundamental forces that make up this universe.  It’s the most power anyone can hold and it’s all right in the palm of his boney hands.

There is a tiny shifting sound from behind him and he looks to see that Blue is stacking his containers neatly by the door.  Then he returns to his lump of sheets and sits impatiently.  Blue is getting bored and restless.  Sans wonders how this guy could  _ possibly  _ be another him.  If it were him there he’d be in heaven.  He could spend the whole time asleep - he wouldn’t have to worry about food or shelter because that’s all just someone else’s problem.  He could just exist without any responsibility… no reputation, no bills, no Papyrus breathing down his neck… what a life…

But this little Sans is  _not_ him.  No, Blue is  _constantly_ moving and Sans as seen him sleep only a handful of times, and even then it would only be for a few short hours.  Sans estimates about ten minutes of peace before Blue comes over and bugs him.  Sure enough, just before the nine minute mark, Blue is right behind him.

Sans is in an overall good mood, what with all the progress he’s making, so when Blue comes over to him, he quietly makes a one-sided conversation with him, explaining all the different parts and their functions.  Blue doesn’t understand a word of it, and many times his eyes sockets just gloss over, but he seems to be enjoying himself.

“alright,” Sans says, feeling satisfied with the adjustments.  “now, let’s see if this peice of junk’ll actually fly.”

Sans closes the panel and steps back.  He sets the dials on the dash and turns the key, pulling Blue back with him as he watches the machine startup.  It rumbles slightly and Sans silently prays that Papyrus stays asleep.  Sans had only imputed settings for a short dimension tear, just to see if it was possible.  He doesn't want to actually send the machine anywhere until he knows he can get it back.   The machine dies down and Sans quickly looks at the log.  If everything is working correctly in the sensors, for about 3.678 seconds, the machine was in another universe as well as their own.  Sans could jump for joy.  This kind of breakthrough is just what he needs.  

“we’re close, blue,” Sans laughs.  “you’re almost home.”

Blue doesn’t understand, but is excited anyways.

Sans has to say, he’ll be a little sad to see the little guy go.  His company is… well… more tolerable than any of the monsters in his universe.  Most of the time friends are either loyal to try to win some favor or are just looking to stab a person in the back - and even those who may be  _ willing  _ to be friends are still too annoying for Sans to be around for too long.  Not only is this Sans quiet, but he’s also genuinely caring.  It could be argued that he’s only doing it because Sans saved his life but… for some reason Sans thinks that Blue really does want to be friends.  It’s… weird.  Must be an alternate universe thing.

Blue is beaming at him again, and Sans rolls his eyes.

“we’re not quite there yet, kid,” Sans says.  “i still need to actually  _ find  _ your universe.”  Sans paces over to the work table where he has his notes strewn about.  This is going to be the challenge of it all.  Finding a quantum signature isn’t easy, and even then he’d need a sample of something from that universe.  He could use just the air around him to isolate his own universes’, but to find Blue’s universe without any substance from that universe is looking for a needle in a haystack.  It’s not like he has anything from Blue’s universe...

...except Blue.

Sans smiles.  Why hadn’t he thought of this before?  It’s so simple!  He quickly spins around and grabs Blue by the arm.  Blue yelps nervously, but trustingly follows Sans anyways.  Sans guides Blue’s hand over to the work bench.  Just a little piece of bone, that’s all he needs, then Sans can figure out just where to send the little guy.  It'll hurt, but Sans  _knows_ that a chip that size will heal in a day - less if he can find some monster candy.  It'll be just like taking blood.

Sans reaches for a sharp tool.

Blue finally catches on to what is happening and jerks back, screaming.  Sans jumps in shock and lunges to grab Blue’s hand, but he leaps back.  For the first time since coming here, Blue successfully summons his magic against Sans, and there is nothing Sans can do to stop the bones from piercing his chest and killing him.

Except when the bone hits his chest it simply stays there painlessly.  Sans checks and his HP is still at one.  It takes a moment for him to realize that the bone is not a threatening white but a soft cyan.  It’s a blue attack?  Sans has seen them done before - hell, his brother  _ loves _ using blue attacks - but most of the time they’re used as traps or distractions, not as attacks.

Sans, in his confusion, loses sight of Blue.  When he finally recovers, bone still lodged in his ribs, he cannot see where Blue has hidden himself.  It takes a moment for Sans to notice the shake in Blue’s covers pile.  Despite everything, Sans smirks.  It's pathetic, but he’s gotten used to it from the little skeleton - at this point it’s cute.

With only one HP to spare, Sans can’t exactly afford to escape, so he simply waits.  Blue may be somewhat healed, but even at full strength he can’t hold this attack forever - and as weak as he is now it’s only a matter of time before Blue succumbs to magical exhaustion. 

Sure enough, the attack fades after only another minute.  Sans then walks slowly over to the lump in the corner.

“blue?”

The shaking in the covers intensifies with Sans’ new proximity.  Sans takes a deep breath and tries to compose himself.  He’s had a lot of practice over the last few weeks calming Blue down, but each time makes him feel awkward and weird.  He crouches down and puts a hand on the quivering sheets.  The tremors instantly go still.

“blue, listen to me,” Sans says firmly.  “calm down, i need to take a small sample of bone to find your universe.  then you can go home, okay?”

There is no movement - no sound of acknowledgement.  Sans huffs.  Blue has shut down again; nothing he says will get through.  He is about to just get up and leave when there is a small shift in the blankets.  Slowly, Blue uncovers himself, his tearful eyes making steady contact with the floor.  Sans slowly puts a hand under his chin and lifts his gaze.  

“do you understand me?” Sans says quietly.  “i’m only trying to help.”  

Blue curls in on himself defensively, and when Sans tries to reach out for him, his magic flairs again.  Sans straightens indignantly.  Flashing magic like that in Underfell is somewhat like giving the middle finger - do it to the wrong monster could and would get someone killed.  Sans lights his own magic, brighter and definitely stronger; Blue’s eyes meet his fearfully, and his magic subsides.

“give me your arm,” Sans says dangerously.

Blue is looking at him warily.  His eye lights have gone out, making his gaze look unstable and uncomprehending.  Sans isn’t entirely sure if he’s getting through, but slowly, Blue holds out a trembling arm and looks away.

Sans smiles at the compliance, feeling accomplished.  “see, is that so hard?”

Blue trembles and Sans runs the tool down his arm.  When the sharp edge strikes a nerve near the marrow, Blue yelps, but other than that, he stays completely still and quiet.  Sans has had these samples taken from him before, and he knows they aren’t comfortable and even border on downright painful, but both he and Blue have suffered much worse.  It is a small price to pay to get the machine working, after all.

When he is done there is a small line of marrow running from the wound in Blue’s arm.  Sans quickly finds a roll of bandages and wraps the cut - it’s not nearly deep enough to actually  _ need _ the bandages, but it seems like caring for the injury might reassure Blue a little. 

Once as he has the sample stored he starts the analyzing process.  The equipment running the data will take anywhere from a few hours to a week to isolate the signature, so in the meantime Sans decides to work on setting up the location module so he can be ready for the next step when the data is processed.

The rest of the night is eerily quiet.  Sans doesn’t understand how this is different from normal - it’s not like Blue is much for conversation.  But when Sans looks back at the skeleton in his care he sees him still sitting in the same position that he’s left him.  Normally Blue would either be observing him or occasionally sleeping - this quiet stillness is nerve racking to Sans in a way he just can’t place.

After a while Sans decides to call it quits for the night.  After saying a quick goodnight to Blue (who didn’t even acknowledge him) and shutting off the lights, Sans goes to bed.

 

\---

 

The next day Blue stopped eating.

At first, Sans just assumed that the stress from yesterday was holding over and affecting his appetite, so he left the small box of pastries by the blanket wrapped skeleton and went straight to work.  It bothers him that Blue never touches the food during the three hours Sans is in the basement - even on his worst days Sans would eat.  It was very... off-putting.

Once again, Sans works in complete silence.

The next day the pastries are untouched and probably bad, so Sans tosses them in favor of these little surface foods called tacos that Blue has shown a liking for.  Once again, Blue elects to stay laying in his bedding than eat.  Sans works while Blue stares at the ceiling.

On the third day, Sans has enough.

“what is your problem!?” Sans yells when he sees the food still untouched.  Blue flinches slightly at the voice, but ultimately does not move, eyes still staring unblinking forward.  Normally yelling would at least elicit a yelp from the small monster.  A week ago Sans would have been happy to see his cowardly behavior go, but now it’s just unsettling.  Sans storms over to Blue and yanks him out of his cocoon.  Not a sound or a movement of resistance - Blue just sits on the floor, hugging his knees.

Sans doesn't understand why he cares so much - it's not like this was ever about getting Blue home.  This is now and always has been about scientific discovery and furthering Sans' research _through_ Blue, not for him.  So why does he give a shit about Blue and his broken psychi?

Sans picks up the little skeleton and stands him up on his own.  He grabs the bandaged arm and Blue flinches hard, but does nothing to protect himself from his imagined dangers.  Sans quickly undoes the wrapping and shows Blue the arm.

“look!” He shouts.  “it’s gone!  there’s barely even a scratch left!  what is bothering you this much!?”

Blue looks over at the arm quizzically, then drops it and curls back up on the floor.  Sans, frustrated, slams his foot into the side of a cabinet.  This only serves to make Blue curl up more.  

Sans is at his limit.  This is so fucking stupid and it is  _pissing. him. off._  This little fucker has survived countless weeks in Alphys laboratory - possibly even  _years_ \- and some little  _scrape_ is what puts him over the edge?  Sans yells incoherently in frustration then turns back to Blue.

“why are you so fucking pathetic?” Sans snips.  “would you just _grow a goddamn backbone_!”

Suddenly, Blue shifts.  At first, Sans thinks it's from fear, but slowly he can hear a small, choked noise.  It sounds like Blue is holding back, but eventually the sound wins out and escapes him.  Is that… Is he… laughing?

Sans is confused.  Has Blue finally cracked and lost his mind?  What did Sans even do this time that caused Blue to go off the deep end?  He had thought they were making progress until this little incident but he's truly gone insane then there is no _way_ Sans can help him.  

I t's an oddly terrifying few seconds before Sans realizes -

Oh.

He'd made a pun.

This is, unexpected to say the least- there isn't a single creature in the underground that likes Sans puns - yet here's Blue about ready to give up on life and all it takes to bring him back is a stupid, unintentional pun?  It's almost funny, and Sans sure as hell isn't going to question it.

Wild grin slowly making its way onto his face, Sans approaches Blue.

"shoulda known that would be how to get to you.  we sanses got funny in our  _bones_.”

The small giggles begin to grow, along with an amused and annoyed look from Blue.  Feeling accomplished, Sans continues.

“i was a little nervous to share my pun collection with ya, but i  _mustard_ up the courage.”

That one actually earns him a humored groan.  Blue is looking Sans in the eye again and he can tell that he's definitely feeling better. It's been a long time since Sans has had an audience that didn't literally try to kill him after the first pun, so he's got  _hoards_ of them stored up.

"you do seemed stressed, though, wanna _taco_ about it?"

Blue shakes his head and groans again, but he’s sitting up enough now that Sans can see his face - he's smiling.

“one more?” Sans prompts with a wicked grin.  Blue shakes his head, but the gentle smile on his face eggs Sans on.  “What kind of tea does Papyrus like?"  Blue is close to laughing already.  "Spaghe-tea!”

Blue loudly groans, but the smile only grows.  His laugh is really cute, Sans decides.  Underfell doesn't have a lot of room for laughing, but apparently this guy didn't get the memo.  When the laughing dies down, Blue returns to hugging his knees, but the life seems to have slipped back into his eyes. 

Feeling accomplished, Sans leaves Blue and continues his work.  The sample should be processed soon, he hopes, and then the final adjustments can be made and put this whole mess behind him.

There are soft sounds behind him, and it takes a while for Sans to notice, deep in his work as he is.  He turns and faces Blue.  He’s… Crying?  Sans doesn't understand how or why Blue is cycling through these emotions.  Apathy, laughing fits, then crying... the emotional rollercoaster going on in this guy's mind must by three miles long.

Sans almost rolls his eyes at his counterpart's crying when he notices something; Blue is still smiling.  Sans watches in awe - he’s never seen someone look this way before - both calm and… not.  Blue looks so fragile right now, like if Sans so much as taps him he’ll break back into his fearful self.

Blue eventually notices the starring.  Their eyes lock for a minute - Blue is judging him, Sans can feel it.  He must have judged him well because Blue gives him a big, toothy smile.  Sans quickly looks away, but he’s smiling too.  He would never admit it even under the worst of torture, but he had been worried for Blue.  If Blue had died… Sans tries to convince himself that it would just be frustrating for him because of all the work he’s put into getting him home.

There is a small pinging sound from the other side of the room and Sans slowly makes his way there.  Sans’ soul jumps in his chest as he reads the results.  A quantum signature has been identified!  And it’s even close to his own. 

Up until this point it had still been a possibility that Sans would not be able to get Blue home - either not being able to find a signature or the universes being too far apart or too weak to travel between.  If that had been the case, Sans doesn’t really know  _ what _ he would have done with Blue.  He’s pretty sure Papyrus wouldn’t want to keep pets, especially another Sans, and he couldn’t just let him go out into the Underground because he’d be killed in an instant.  The only option Sans would really have would be to do what he had originally planned and kill the poor bastard; but Sans doesn’t have to worry about that now because he found it!  He found Blue’s home.  All that’s left is for him to draw up a map for the machine to follow and then he can put this whole mess behind him.

Sans smiles and turns to his counterpart.

“good news, blue.  you’re going home.”

**Notes for the Chapter:**

> Woah, boy this chapter went through some revisions... Nothing major, I just kept tweaking it trying to get it right. As always, hoped you enjoy~~!


	5. Pappy isn't very Happy

**Summary for the Chapter:**

> Blue escapes and makes a friend

**Notes for the Chapter:**

> This chapter was made possible by Sora_Tayuya, who "suggested" it to me in a comment. It was written after the story was complete, so if it seems a little out-of-place that might have something to with it.

After that little episode is over, things go pretty smoothly.  Blue mostly goes back to himself, though Sans still feels he is being a bit cautious around him.  It doesn’t matter, he tells himself.  He ignores the feeling of hurt every time Blue flinches when he comes too close, or when he reaches for a screwdriver.  Other than that, though, there are no hitches that are stopping Sans from getting the machine functional.

That is, until one day, when Sans makes the mistake of leaving the lab door unlocked.

Sans had the day off that day and he spent most of it working with the machine and Blue.  He only stops when he gets an angry text from Papyrus to stop boondoggling and go get the groceries.  Sans thinks he’ll only be gone for a moment, so there isn’t much reason to lock the lab door - Blue is asleep and no one knows about the lab so what’s the danger?

He buys what they need - and a little extra for Blue that he won’t tell the boss about - and is making his way home when he hears a loud cry of distress.

It sounds like Papyrus.

Dropping the groceries Sans rushes home, ready to defend his brother from whatever and whoever has attacked him - except, when he gets there…

“SANS!?  DID YOU CLONE YOURSELF?”

Sans stops and gasps in horror.  Papyrus is standing at the doorway, and Blue is wrapped around his midsection in tight, unreciprocated embrace.   It looks like he’s been crying.  Papyrus looks almost exactly like a cat that is about to be dunked in water - the whole thing would be hilarious if it wasn't just so frightening.

Shit.

Why hadn’t he locked the damn door?

Papyrus is glaring at Sans, waiting for an explanation.  Papyrus is a lot of things - intelligent is not one of those things, and it would take _forever_ to explain the situation; not to mention having to admit to his failure at Alphys lab.  Well, Papyrus has already come to his own conclusions, and to him, scientists are all the same thing, so it doesn’t matter that Sans is a physicist and has literally no idea how he would even _start_ to go about cloning himself.  

So Sans takes a deep breath and 

“yes.”

“ARG, WHY!?” Papyrus yells, prying the small Sans off and shoving him at Sans.  Sans catches him and holds him tight.

“heh, you seem mad - i'm _beside myself_.”

“SANS!”

Sans shrugs and looks around, self-conscious of anyone seeing the tiny skeleton who can't defend himself.  Blue is shivering and he looks as though he'll jump at Papyrus again at any moment, and if he does it'll be the last thing he'll ever do with the way Papyrus is looking at him.  “can we continue this conversation inside?  i’m getting really chi-”

“SANS I SWEAR IF YOU FINISH THAT SENTENCE WITH ‘TO THE BONE’ I WILL KILL YOU BOTH.”

Sans jumps back at the harsh tone, all the humor leaving his face.  Papyrus is pissed.  Sans has done a lot to piss off his irritable little brother - he's filled the kitchen with mustard, he's fed leftover pasta to the stray dog Papyrus hates, he's overslept his post _countless_ times - but then it was only _him_ getting punished for those stupid actions.  This time Blue's life is on the line too, and the skeleton doesn't even seem to realize it, just staring starstruck at Sans' murderous brother.

Finally, Papyrus breaks out of his rage and looks over the Sanses.  Papyrus sighs, opening the door.  Sans takes Blue by the hand and half guides half drags him into the house.  When the door is shut, Papyrus begins pacing the room.  Sans flops himself down on the couch, and he maneuvers Blue to sit by his feet.  

This is bad.  This is really bad.  Sans can practically see the wheels in his brother's head spinning, albeit not very fast.  Sans knows that Papyrus is thinking to kill Blue here and now - he's known his brother well all his life and Sans can read him like an open book.  The only thing stopping him right now is Sans.  Papyrus would do a lot of things, but if he thinks Sans actually _worked_ for something for once in his pathetic life then he is reluctant to destroy it.  Sans just hopes that is enough to offset his brother's instant hatred of him. 

Papyrus is still pacing and Blue still seems like he is a moment away from rushing back to him.  Sans uses a foot to pin him to the couch as Papyrus finally finds his words.

“IS THIS WHY YOU WERE CONSUMING SO MUCH FOOD?”

“yes.”

“AND THE OVERPRICED ELECTRIC BILL?”

“yep.”

“SANS!”

Papyrus looks dangerously close to becoming violent, and while Sans is _sure_ his brother would _never_ kill him, Blue is a different story.  Sans isn't sure exactly how Papyrus feels about the little pathetic Sans, but he's sure that after Blue _touched_ him (something even Sans himself isn't allowed to do) it's probably not positive.  Sans still isn't entirely sure why he wants to protect the little guy, but he really does.

“l-look, boss, i’ll pay you back, i swear,” He says, praying that would be enough to placate his brother.  Evidently not.

"SANS, THAT ISN'T THE ISSUE HERE!" Papyrus snaps before taking a deep, calming breath and looking back to Sans. “I WANT YOU TO GET RID OF IT,” 

“believe me, i’m trying,” Sans mutters, Papyrus glares again and Sans addresses him, “boss, please, i only need a few more weeks - a month, tops - and he’ll be gone, i promise.”

Papyrus grumbles, obviously not pleased.  Sans shifts nervously.  If Papyrus doesn't want Blue to live, there's very little that Sans can do to protect him.  Sans is strong; Papyrus is stronger, and the fight would probably break what fragile bond they have.  No, he has to convince him to let him keep Blue - just until the machine is running and he can send him home.  Sans is about to plead with his brother again when Papyrus yells.

“WHERE HAVE YOU EVEN BEEN KEEPING HIM?”

“basement.”

“WE DON'T HAVE A BASEMENT.”

“we don't have a basement _that you know of,_ ” San corrected.

“WHA- IS THAT WHY THE PROPERTY TAX IS SO HIGH!?” Papyrus shouts, causing Blue to flinch hard.  Sans tries to discreetly put a hand on his shoulder to reassure the shaking skeleton, but Papyrus notices and comments, “WHAT IS WRONG WITH IT?  WHY IS IT SO… SQUISHY?”

Sans has to think for a minute. The truth about Alphys would get him punished and contradict the clone theory, so Sans just shrugs, “dunno, it's not that bright.”

Of all the things, _that_ Blue has to understand.  He makes a small, annoyed noise and bats at Sans’ legs.  Sans rolls his eyes and laughs nervously, looking to Papyrus to gauge his reaction.  Papyrus looks somewhere between amused and annoyed.  Eventually, he lets out a long sigh.

"YOU INSIST ON KEEPING IT?" Papyrus asks, exasperated. 

"just for a little while longer, boss," Sans says quickly.  Papyrus sighs in defeat.

“REGARDLESS, IT WILL BE STAYING HERE, IN THE HOUSE, UNTIL  YOU ARE DONE WITH HIM.”  Sans flinches in shock.  Is… Is he serious?  Well, that certainly is... unexpected.  Sans looks at his brother with complete disbelief and Papyrus huffs.  “I WILL NOT HAVE A GUEST STAYING IN SOME PREVIOUSLY UNKNOWN BASEMENT.   I WILL NOT BE ACCUSED OF BEING A BAD HOST, EVEN TO STRANGE CLONES OF MY USELESS BROTHER.”

Sans blinks slowly.  Then nods.

“s-sure, boss,” Sans says, still reeling from the apparent 180 turn in situation.  “thanks.”

“JUST MAKE SURE IT STAYS OUT OF TROUBLE,” Papyrus snaps.  “AND YOU  WILL BE PAYING FOR ITS MEALS FROM NOW ON.”

“fair ‘nough,” Sans says.  He'd already doing those things anyways, but the confirmation is enough for Papyrus to let the issue drop.

Papyrus grumbles.  He is obviously still not _pleased_ with the situation, but he doesn't voice it.  Instead, he trudges back out the door, mumbling something about needed to watch over the dog squad.  Sans lets out a breath he didn't know he had been holding and turns to Blue.

“do you even realize how close you came to being dust, blue?”

Blue doesn't seem to be listening, he is still looking towards the door where Papyrus has just left.  Sans doesn’t understand what the little guy’s infatuation with his brother is - certainly he knows by now that it isn’t _his_ brother.  Right?  There have certainly been times when Blue didn't understand extremely basic concepts.  Maybe Blue doesn’t even know he’s in another universe.  Now that Sans thinks about it, It _is_ possible that Blue doesn't know the difference between his brother and Sans'.  The little guy does have a habit of running more on emotion than logic, and with his emotions are messed up as they are.

Sans sighs.

This is too difficult - he can’t deal with his _own_ messed up emotions, how the hell is he supposed to deal with Blue’s?  Since the day he entered Sans’ life, Sans has had to walk on eggshells not to terrify him and it's been so long and he _isn't getting better._   Physically wounds heal quickly with monster food and rest - but psychological scars last a lifetime and Sans has no idea how to treat _those_.  

So then, the best thing to do now is to try to get Blue home as soon as possible, that way someone _else_ can help him - hopefully someone more emotionally capable than Sans.  It’s not like Sans has a choice anyways;  Papyrus isn’t going to put up with two Sanses for long.  

Sans yawns.  What time is it?  Who cares, it’s bed time for Sans.  Today has been exhausting, and maybe with some sleep the answer will become clear.  Maybe.  Probably not.

“come on,” Sans says, prying Blue away from the door.  “i guess you’re staying in my room.”

Sans leads Blue up the stairs and to his room.  It’s still a mess, but Sans doesn’t care - Blue can judge him all he wants, he's too tired to care anyways.  Sans thinks to teleport down to the lab and get Blue’s blankets, but he’s just exhausted.  He’ll get them in the morning - it’s not like Blue is gonna sleep anyways.

Sans flops down on the unmade mattress and closes his eyes.  He’s out almost as soon as his head hits the pillow.

 

\---

 

Sans wakes to a loud bang.  He bolts up and looks around the room.  Everything is right where it is supposed to be except for one crucial detail - 

\- Blue is nowhere to be found.

Shit.

“SANS!  GET IN HERE _NOW!_ ”

Double Shit.

Sans jumps out of bed and rushes into Papyrus’ room, praying he'll make it in time.  When he reaches the room he gawks at the scene.  Blue is pinned against the wall with blue magic, squirming and struggling.  He is as panicked as Sans has ever seen him, kicking and clawing furiously at nothing trying to somehow break free.  Papyrus looks at him furiously, eyes blazing red.   Sans can tell that if he didn’t act quick it was all over for little Blue.

“w-what happened, b-boss?” Sans stutters.

“YOU’RE LITTLE CLONE WAS TRYING TO GET INTO MY BED!” Papyrus shouts, spitting every syllable at the small skeleton pinned to the wall.  Blue doesn't really notice; he's slowly running out of steam and beginning to falter in his struggles.

Sans mentally kicks himself.  He should have known this would happen from how Blue was acting before.  He should have locked the bedroom door, ro tied Blue to the bed post or _something._ But it's too late now - Sans just has to hope that he can salvage this situation before someone dies, namely Blue.

“s-sorry, boss,” Sans says the first thing that he can think of.  “it won’t happen again.”

To his relief, that is enough.  Papyrus huffs and his glare shifts from Blue to Sans.  He lets the hyperventilating Blue down off the wall and composes himself, head high and arms behind his back.  “SEE THAT IT DOESN’T” Papyrus flings Blue at Sans, who catches him none too gracefully. "I WON'T BE AS FORGIVING NEXT TIME."  With that, Sans stutters a quick goodnight and shuffles awkwardly out of the room.  He returns to his room and places the quaking Blue on his bed.

“what the _hell_ !?”  Sans yells.  “what the _hell_ were you _thinking_!?”

Tears streak Blue’s eyes and Sans groans loudly.  His covers his face in his hands.  How the hell can he explain this to him?  Blue has the mind of a child and Sans is _terrible_ with children!  He doesn’t understand and Sans has no idea how to _make_ him understand.

He looks back and Blue and takes a deep breath.  If he were in Blue’s place, what would make him listen?  Sans closes his eye and thinks.  Several seconds pass and slowly Blue has calmed down.  Finally, Sans nods and looks back up at his charge.

Sans places his hands on Blue’s shoulders and he tenses, but quickly relaxes when his face lights in recognition.

“sans, listen to me,” he says lightly.  “that isn’t your brother, okay?”  Blue is looking at him with a confused look, so Sans repeats himself, “that person in the room next to us is _not your brother._  nod if you understand the words I am saying.”

There is a long pause as if Blue is trying desperately to digest the sentence that was said.  Just as Sans was giving up hope, Blue nods his head, questions still dancing in his eyes.  Sans does his best to guess what they are and answer them.

“my name is sans, but i'm not you.  his is papyrus, but he is  _not your brother._   he is _my_ brother.  your name is sans, and your brother is back in your universe.”

Sans eyes have yet to glaze back over in incomprehension, but he doesn’t respond as if he understands what the words mean.  If it were anyone else, Sans would just say they were confused, not lost.  With a long sigh, Sans continues.

“i know he looks like your brother, but he’s not.  and he will hurt you if _ever_ try anything like that again, okay?”

Sans nods almost instantly that time, then looks down.  There is a question he wants to ask, Sans is sure of it, but finding his speech after such a long period of disuse must be exhausting.  Sans is silently rooting for him, wanting  _desperately_ to hear his alternate self speak.  An eternity of silence engulfs them- Finally, Blue looks back up and he opens his mouth.

But no words come out.

Sans deflates.  Blue lowers his head again in defeat and tears prick his eyes.  Sans is at a loss - there is just no way that he can communicate with someone who refuses to speak.  Sans isn't telepathic and he isn't particularly empathetic either.   There is no non-verbal communication that Sans still knows and even if he did teaching the other would take far more time than he has.  Sans, with nothing else left to try, does something he never thought he would do.  He reaches forward and pulls Blue into his arms.

He is met with instant stiffness and confusion.  Blue makes a small keening sound, then buries himself into the other like he did the first day they met.  Small sobs leave him and Sans rubs his back like he remembers doing for Papyrus when he was little.  

For the first time in his life, Sans contacts with another person - suddenly he can see everything from Blue's perspective.  He is so lost, and Sans doubts that he would understand everything about the alternate universes even if his mind wasn't a mosaic.  Sans imagines what it must be like, to be broken and alone in an unfamiliar place yet with semi-familiar people - even the sanest man in the underground would think he'd gone insane.  

Blue had thought he had found his brother, and to have even that taken away from him again must be painful.  Sans finally has a small grasp of understanding of the small creature in his arms.  He must be so...homesick...

Suddenly, Sans knows what Blue wanted to ask.

“you want to know when you're going home, don’t you?"

Sans can feel blue nod against his shirt.  

Sans finally, _finally_ understands.  Blue had been listening.  Blue had been watching.  He knows that Sans has been trying to get him home and now he is asking for some kind of confirmation.  Blue wants to know that he's really going home - that everything is going to work out.  There have been many times in Sans' life where he needed and was denied that confirmation, that everything was alright and that everything will work out. 

So he gives the little skeleton what he wants.

“i’m going to get you there soon, okay,” Sans says quietly.  “i promise.”

**Notes for the Chapter:**

> Meh, this chapter could have been better. Oh well, it's kind of filler anyways. I might come back and edit it later.
> 
> Next chapter, though... oh boy. You guys just wait. Blue is going home.


	6. Going Home

**Summary for the Chapter:**

> Blue goes home.

Sans is practically _racing_ to finsh.   Now that he has made a promise he absolutly _refuses_ to let any time go to waste.  He wants to get Blue home as fast as possible, for a lot of reasons.   Papyrus has been growing more and more impatient to get rid of Blue, and Sans fears that if he doesn’t find a way to make this work he’ll dust blue himself.  At least Blue has been making an effort to stay away from Sans' brother since the first night.

It takes almost to the end of Papyrus' deadline, but Sans makes it.  With the final adjustments, the machine is totally operational and ready for use.  Sans couldn't be more pleased with himself.  No one has ever attempted inter-universal transportation.  Yet not only did Sans pull it off, but he is about to send another living being through.

Sans guides Blue to the machine and begins putting in the exact coordinates.  With the correct equations and a little luck, this should put him directly at the edge of Snowdin.  It’s rigged so that only a minute after he opens the door, the machine will return, that way Sans can get his hard work back.  Sans looks over to Blue, who is shaking again, this time in anticipation as well as some ill-concealed fear.  Blue trust Sans enough to get in the machine, but they both know there is always risk of failure even though Sans has fool proofed the machine.  He won't take any risks with Blue's life.

A sad smile forms on his face.  He really will miss the little guy, no matter how weak or annoying.  Somehow, that’s part of his charm.  He’s heard of other monsters taking in ‘pets’ before, and they describe similar feelings to the weaker creatures.  That a kind of bond forms from caring for a smaller being.  Sans had never understood until now -but Sans doesn’t need a pet, nor does he actually want one.  Blue is a novelty, a means to get to another universe, nothing more...

Still, maybe once as he’s perfected the machine he’ll come visit Blue.  Just to make sure he’s alright.

Sans gives Blue an affectionate pat that lingers a little longer than he had intended, then he steps out of the machine.  Locking the door tight, Sans turns the dials on the outer control pad and initiates the count down.

Sans is confident that this will work, it has to.  Everything is in place, his calculations have been double and triple check, there is no possible error that can occur.

Blue watches Sans from the inside.  It's been a long time since he first came here, and its been one hell of a journey for both of them.  Sans lifts his hand and gives him a wave goodbye.  Blue smiles and mimics the gesture

The machine has started to hum, emitting a soft black-light glow.

Something's wrong.

It’s not supposed to do that!

Sans dashes to the controls to abort the run.   He slams his hand on the abort button, but even after the machine has powered down the light is still there.  Sans can feel a pulse in the universe that almost knocks him off his feet.   Blue feels it too and begins to bang on the door.  Sans grip on the panel tightens, trying to steady himself against the temperal distrubance.  Before he can even attempt to hit another button there is another wave, bigger this time.  It scrambles his thoughts and the next thing Sans knows he's on the ground. 

Sans can see it now.  Spots of complete and total darkness are breaking into the fabric of reality.  It's the void.  

Close to panicing, Sans breaks through the spinning in his head and makes it back to the controls.  He has to stop the tear before it rips his reality apart!  Sans' vision is fading and he can just barely hear Blue screaming in terror from inside the machine.  Even with his senses numbed he can tell the tear void is growing.  He quickly runs his fingers across the places where he knew there were buttons and prayed to any god that would hear him that he hit the right ones.  

Finally, the void stops.

Sans sinks to his knees and slowly lets his sight return to him.  Blue is crying from inside the machine, and for once Sans doesn't blaim him.  That was close.  Way too close.  Sans slowly gets to his feet to unlock the door, but before he can reach it there is another pulse in the universe.

And it is overpowering.

The machine jumpstarts and begins to shake.  Sans leaps back in shock, watching as pieces of the lab tile are enveloped in the void.  Blue is still inside.  Sans dashes forward, but there is nothing he can do.  Sans barely makes it a foot forward before the entire lab is enguffed in overwhelming darkness.

\---

Dark, darker, yet darker.

Sans slowly opens his eyes to see an expanse of nothing his mind can comprehend.  Oh God, what happened? Is this the void?  Panic takes over and Sans flails to find something tangible.  He finds it rather quickly, as throwing his head back he slams it against something cold and hard.  Attempting to calm his breathing, Sans slowly lets his senses adjust. 

Snow.

He’s lying on snow.

He blinks slowly, trying to alleviate the sense of vertigo clouding his mind, and the trees of Snowdin forest slowly come into focus.

Except… not?

He can’t explain it, but the trees just look so much less… menacing.  They’re still evergreens, but they are so much brighter and cleaner.  He sits up slightly, rubbing his temples.  He knows this place.  It’s just outside the ruins, just before his station but… where is everybody?  This time of day the dogs should be out patrolling. Did he hit his head on the way down and time just moved on without him?

No, something's definitely not right…wherever he is, it’s not his Snowdin.

Does that mean that this is-

“it definitely came from over here.”

Sans' soul stops.  A voice.  Someone is near by.

"...naw, i got this... you go home... i'll check it out."

Sans sits up straight and attempts to get his feet under him; unfortunately it doesn’t seem as though he’s ready for this, as the next thing he knows, Sans is flat on his face.  There are footsteps drawing nearer, and there is no way he can defend himself in a fight right now.   Shit.  There has to be something he can do before…

“hey, buddy, it ain’t smart to be wandering around the forest in the middle of-” Sans turns and his eye lights go out entirely.  The towering monster with a familiar face has a similar reaction, as he cuts off mid-sentence, letting the cigarette sticking out of his mouth drop and sizzle in the imaculate snow.

Papyrus.

It’s a tense few seconds before Sans realizes this is definitely not his Papyrus.  From the quiet voice to the laid back stance, to the orange hoody that is clashing horrendously with the blue bandana wrapped around his neck.  Sans holds his breath.  While his Papyrus would have beaten the living daylights out of him for sneaking out of the house without telling him, he has no idea what this Papyrus is like or how he'll react to seeing him.  Maybe he’s friendly, maybe not.

Like hell Sans is sticking around to find out.

“sans?” The word is whispered lightly, laced with disbelief.  Sans barely hears it as he jumps to his feet and makes his wobbly escape through the trees.

“sans? no!  wait!”

Sans can hear this universe’s Papyrus running behind him.  Sans can barely stand streight and running is even worse.  Sans knows he has no chance of outrunning him by foot with his current health, so he takes a shortcut he memorized from his own universe -

\- only to end up teetering on the edge of a gaping chasm.

Sans throws his arms back, trying to regain his balance, but to no avail.  The snow gives way under his boots and he tips over the consuming pit.  His eyes squeeze shut as he braces for the oncoming fall.

He barely registers the hand that wraps around his bony wrists and pulls him back.  Saved from almost certain death, San finds himself wrapped tightly in his savior's arms.

“sans, sans... oh my god i thought you were… i thought” This Papyrus’ low and soothing voice wraps around Sans, and he is sure that he hears a waver in that voice, like his brother’s counterpart was about to cry.  It's weird.  He seems to notice Sans’ discomfort and let him go, though this time Sans doesn’t even make an attempt to escape.  There is no way he can outrun this guy, and he evidently can’t shortcut across an unfamiliar universe - no matter how eerily similar to his own.  He is trapped.  Seeing the wariness in Sans’ eyes, Papyrus reaches out a hand (ignoring Sans’ hard flinch) and places it on his shoulder.  “sans?  it’s me. your brother?”

Sans is confused for a moment, until it clicks.

The machine worked.

This must be the universe Blue came from, and that means that, by extension, this is his Papyrus.  A Papyrus who has been missing his brother for a very long time.  With the way that he’s looking at Sans, there is no doubt in Sans’ mind that this Papyrus thinks that he is his Sans.  The next question is, what to do with that?

He knows literally nothing about this universe, other than the fact that someone as soft as Blue managed to survive in it.  Sans only has his universe to use as a reference to make assumptions about this one, and so far he can't tell if this Papyrus is more like his or more like Blue.  Since there is no way of knowing for sure, Sans finally decides to take the safest route.  He knows that no matter what universe, Papyrus probably wouldn't harm  _his_ Sans.

Sans slowly tries to mimic Blue’s facial expressions - softening his eyes to look as pitiful and hopeless as possible.  If his Papyrus could see him now Sans is sure he wouldn't be sleeping inside for a month- but this Papyrus merely looks at him with tears in his eyes and pulls him into another embrace.

“sans... oh god i was so worried.” he says quietly, “i thought i’d never see you again.”

Sans doesn’t really know what to do.  He’s not exactly well practiced at the art of monster contact.  The only person to hug him in the last decade has been Blue…

And where is the little pest anyways?  Did he make it through to this universe too, or did he…

“sans?” Papyrus looks at him strangely.  His emotions seem to steady themselves, and he looks at Sans with a searching gaze.  It takes all of his strength for Sans not to shift under his stare.  “are you okay?”

Sans’ mind goes blank.  Does this guy want an answer?  Blue hasn't spoken a single word when he was around Sans - Sans had even started to think that he never could in the first place, but apparently Papyrus thinks he can, and Sans has absolutely no idea how to respond to this.

Suddenly the world tilts on its side and Sans’ head weighs a hundred pounds. Closing his eyes he tries to block out the new hammering in his skull.  Sans yips and struggles as he feels his body leave the ground. Papyrus arms wrap around him and holds him close to his chest.  At a loss for what is happening, Sans tries to squirm out of Papyrus’ grip, but quiet, calming noises force him into surrender. 

His eyes were heavy like they had never been before - different from his usual perpetually tired state.  Warm darkness begins to seep into his eyes and into his bones, beckoning him.  Sans finally gives up consciousness for the embrace of sleep as Papyrus carries him through the village.

**Notes for the Chapter:**

> Final Chapter tomorrow.... OR IS IT? I've decided to continue this work with a couple of sequels, so stay tuned for more! ;)


	7. The Way Back Home

**Summary for the Chapter:**

> The True Ending

**Notes for the Chapter:**

> Happy Holidays everybody!

When Sans returns to consciousness, he barely registered where he is.  The room is sparsely decorated, with bright colors plastering the walls.  Bookshelves lined with children's books and encyclopedias cover one wall while the other is protected by tiny dolls.  It looks almost like a dumb child's room, except everything is kept very tidy and neat.  Despite the very orderly surroundings, though, there is a fine layer of dust covering everything - the type of dust that can only come from months of disuse.  But the room looks so loved, why would the owner stop using it…

Unless.

Finally the memories of the last few hours sink in and Sans leaps off the bed, which he only now realizes is shaped like a sail boat.  This has to be Blue’s room - There is no doubt in Sans' mine.  From the pastel walls to the overall calm and dorky feel, this place just has to be his.  That means that Papyrus brought him home.  Does he still believe that Sans is his brother, or is he going to try to keep him as a pet?  A replacement.

Sans frantically lunges for the door, only to be cut off when it opens and reveals a very laid back Papyrus carrying a tray of food.

“heh, thought i heard you running around up here.”

Sans tries desperately to calm his breathing.  If he wants the Papyrus’ help and sympathy, he has to keep pretending to be his brother.  If he found out Sans’ true identity, there’s no telling what will happen to him. He tries to fake an excited smile like he’s seen Blue do thousands of times when he went down to the lab. Papyrus gives him a strange look and guides Sans back to the bed. 

Papyrus places the tray on Sans’ lap.  The bowl contains a thin broth that Sans would under any other circumstance be sure was poisoned, but with hunger clawing at him after being unconscious for Asgore knows how long, he can’t help but shovel the liquid into his mouth.

While he’s eating, he notices Papyrus staring.  He tries to ignore the sockets burning into his back, but soon it becomes too unbearably nerve-wracking to ignore.  Sans meets his pseudo brother's eyes, silently questioning.  Papyrus shrugs and looks away, letting Sans go back to his meal.

It doesn’t take long for him to finish, and when he does he just sits there and looks at the empty bowl.  What happens now?  Would Papyrus interrogate him?  If he did, should Sans answer?  Would answering give him away, or would the silence only serve to make him look guilty? 

Sans once again feels Papyrus staring at him.  Sans still doesn’t know much about this Papyrus.  He doesn't act much like his own Papyrus, but it could be due to the fact that this one lost his Sans, and now thinks he’s found him.  Sans tries to think what his brother would do if the same happened to him - though the answer he keeps coming up with is berating him for disappearing in the first place.  This loving attention is far too foreign to Sans, he simply doesn't know the proper reation or reason behind it.

This Papyrus is so different from his own.  He is so laid back and has an all-around carefree feeling to him.  There is no way he’s in the royal guard in this universe, he’d be eaten alive.  Though, from what Sans has seen thus far, this is an overall softer reality than the one he originates from.  Maybe that’s just one of many differences; Maybe this world doesn’t need a royal guard.

Sans thoughts are cut off by a low laugh.

“heh, so, uh,” Papyrus starts awkwardly, “you’re not my brother, are you?”

Any warmth that this house and the food had brought him suddenly leaves Sans’ body.  His eye lights disappear completely and the bowl slips out of his fingers, shattering on the floor. This is it. He’s been caught. Papyrus no longer has any reason to keep him alive unless it’s for information on where his brother is.  But Sans doesn’t _know_ where Blue went! Would this Papyrus believe him if he tells him that?  No.  Sans often sits in on his brother’s interrogation sessions, and he knows for a fact that Papyrus doesn’t stop until he either gets a tangible answer, or the prisoner is dead.  He’s watched what happens when Papyrus doesn’t get his answer, and at times it makes what Alphys does in her lab look _tame_.  The only difference is that nobody leaves the shed alive - and Sans isn’t about to experience that first hand.

Near panic, Sans pushes himself off the bed and dashes for the door.  Unfortunately, it seems Papyrus was prepared for this, because as soon as Sans’ fingers touch the knob he is knocked to the ground and held there.  Pinned and helpless, Sans struggles under the much larger skeleton’s grasp. Papyrus makes no move to stop him, he simply holds him down as Sans kicks and screams and thrashes. Sans will _not_ allow himself to be captured - not without a fight. Slowly, Sans’ body loses momentum and his struggles become more like jerky twitches.  It’s only then that he realizes that Papyrus is speaking.

“-n’t hurt you,” Papyrus’ voice breaks through Sans’ clouded mind.  Sans turns slightly and meets his captor’s eyes.  They are cold and calculating, nothing like the warm Sans had seen when Papyrus first found him in the woods.  “...are you done?”

Not even close. 

Sans quickly summons a wall of bones and sends them into his faux brother.  It’s only through quick reflexes that Papyrus manages not to get hit, but it gives Sans just enough time to rush out the door.  He tumbles down the stairs, feeling a light breeze as several bones fly by his head.  Just as he reaches the front door, his soul turns blue and he is dragged back to the other Papyrus.  Before he reaches Papyrus’ outstretched hands, he closes his eyes and thinks very hard about the place where he first woke up.

Then he slips through a shortcut to the clearing. 

Sans falls to his knees and pants heavily.  That was… close.  Way too close.  He can still feel beads of sweat rolling down the side of his skull as he huddles and desperately tries to calm his nerves.

He has to find Blue.

And that's going to be hard because Sans has literally no idea where he could be.  He doesn’t even know if Blue or the machine made it through to this universe but he knows damn well that Papyrus won’t stop hunting him until he has his brother back. 

As Sans makes to stand, he feels a hand on his back.

“g o i n g   s o m e w h e r e?”

Sans doesn’t even have time for the dread to spiral up his spine as he is hauled off the ground and slammed into a tree.  Boney fingers make their way around his neck and Sans’ hand instinctively follows them to try to loosen the pressure. 

One of Papyrus’ eyes is lit with magic that looks suspiciously like Sans’ own.  How the hell did he get here? Papyrus can’t use shortcuts.  Sans is the only one. 

That doesn’t even matter right now, as even though Sans doesn’t have lungs to breathe, being held up by his neck is still not great for his health.

“s-stop!” Sans chokes out, “i-i’m s-s-sorry.”

Papyrus eyes him warily, then sighs and lets Sans fall gracelessly to the ground.  Sans rubs his neck and looks up at the taller skeleton.  Papyrus has shoved his hands into his pockets and is looking at Sans in a distantly contemplative way.  It’s hard to tell what he’s thinking like this - he could be wondering about Sans’ scars or he could be debating what would be the most painful way to end the little imposter.  Sans shudders and Papyrus brings a hand to his own face.  Slowly, Papyrus looks at Sans decisively.

“so,” Papyrus starts, “if you’re not my brother then do you… know where he is?”

Sans shakes his head quickly and Papyrus gives him a skeptical look.  Papyrus’ hands are fiddling with the fabric around his neck absently, but it still looks like he could snap at any minute and attack, so Sans speaks.

“h-he came here with me,” he says quickly, “but we got…separated.”

“separated?”

Sans nods again. “i got the machine working and i was trying to send blue home… but there was a-an accident and…” Sans is scrambling for words, but apparently he’s said enough for Papyrus to understand because he nods.

“you were trying to send my brother back?” Papyrus says, and Sans confirms with a nod, “why?”

Sans opens his mouth, but then shuts it.  How the hell is he supposed to answer that!?  He genuinely doesn’t have an answer and now if he can’t give the right one _right now_ then -

“don’t get me wrong,” Papyrus continues.  “i’m glad you did, really glad - it’s just, well, you don’t seem like the type of guy to do something nice without wanting something.”

He isn’t.  Sans could say that he was using Blue to further his research, as that is the closest to an answer he has, but if he says that how will this Papyrus react?  Sans looks at Papyrus pitifully and he curses himself for his weakness.  He shouldn’t be this scared of him, but this guy just looks so much like his brother, and if it were his brother the conversation would consist of mostly screaming and attacks…

Papyrus shrugs.  “whatever,” he says.  “it doesn’t matter. where do you think my bro is?”

Sans looks down.  If he’s not in the void begging for death…then…

“i set the coordinates for the edge of Snowdin - just before waterfall; if the machine worked like it should, he’ll be somewhere near there.” Sans says.

Papyrus nods and extends a hand to help him up.  It takes everything Sans has not to flinch at the offered appendage.  He opts to lift himself up rather than take the stranger-with-his-brother’s face’s hand.

Sans looks down at his feet, while Papyrus moves awkwardly towards him.

“shortcut?” He asks, and Sans nods, allowing Papyrus to put his hand on his shoulder. Papyrus teleports away, towing Sans along after him.  They are just before the mouth of Waterfall, yet there is no sign of the machine anywhere.  Sans feels a sinking feeling in his chest; he tells himself that it's just because Papyrus will probably kill him if anything has happened to his younger sibling.

“let’s split up and look around.” Papyrus says, “we’ll cover more ground that way.”

Sans looks at him briefly, then nods.  The expression Papyrus wore left no room for argument.  Sans instantly walks off in one direction.  He doesn't even have to look behind him to know that Papyrus has run off in some other direction, desperate to find his brother.  There is no doubt in Sans’ mind that Papyrus knows the possibility of Blue’s death, and the prospect bothers Sans too, for some reason.

And that's just the strangest thing to Sans, actually caring about another person.  The closest he's felt to this would be his feelings towards his brother, but even then it was more of a symbiotic relationship - Sans relying on Papyrus for protection and all.  Blue has done nothing but take from him, and Sans doesn't even expect any kind of reward or karma from it. 

What has gotten into him?

Before he can reflect further, Sans sees a break in the trees.  It's unnatural - as if someone had just carved a hole in the trunks and branches.  Sans rushes forward and a surge of relief fills him.

The machine.

He slides down the crater and begins circling the dented and broken metal container.  There is no way he can possibly repair this; which begs the question of how he is going to get home, but for now-

“blue!”

Sans pries the door open and desperately looks around for a shrunken version of his own form.  When he finds no one, he looks around with sickening apprehension for a pile of dust.  Sans breaths slightly when he realizes that the floor is clean.

He must have left the machine.

Sans looks outside for any signs of footprints other than his own, but unfortunately the snow has covered all signs of a previous life in this area.  Sans slams his hand against the metal of the machine.  Blue’ll freeze to death out here like this, unless he’s made it back to Snowdin, but if he could do that, then why didn't he do that the night before?

“huh, so you found it?”

Sans jumps and spins around.  The other Papyrus has his gaze locked in the machine, hands trailing down the side.  He reaches the door and, like Sans, opens it to find nothing inside.

“couldn’t find him.” Sans says, shoving his hands in his pockets and kicking at the marsh plants,“blue probably panicked and ran. he could be anywhere in the underground by now.”

Papyrus turns to him with a curious expression.  “blue?”

“uh, sans, i mean,” Sans says awkwardly. 

Now what are they going to do?  Blue really could be anywhere by now - Sans isn’t just saying that to be lazy.  Papyrus seems to realize this too, and leans back against the machine.  The two sit there, thinking, just trying to make sense of the situation and plan their next step.

It wasn’t until a small whimper cuts through the tense air that either of them move.

Papyrus seems confused, but Sans instantly recognizes the sound.  He darts towards the source of the noise, something hidden away in a small indentation in the wall by the clearing, covered by thick bushes and vines.  Up close, Sans could tell several of them had been snapped away. 

“blue?”

Sans pushes the leaves out of the way.  Sure enough, the tiny skeleton is curled up in there.  Sans lets out a breath of relief. 

“sans?” Papyrus calls.  Sans isn’t sure to which of the two he is referring, but the moment Papyrus sees his brother, he brushes past Sans to get to him.  Papyrus runs a hand across Blue’s face, tracing the many cracks and scars that cover him.  Blue looks away from Papyrus, ashamed, but Papyrus grabs the little skeleton and pulls him close. “you’re alive. thank god…thank god…”

Papyrus is mumbling something and holding Blue close.  Blue is lost for a moment, but slowly he begins to tear up too, and returns the embrace.  Sans, feeling like an intruder, backs away.

Sans returns to the machine and begins looking it over.  It’s trashed.  He was hoping that with a second look the machine might actually be repairable - but no. There is no way without his lab that he will _ever_ be able to repair this.  Sans grumbles and kicks the mangled heap of metal.  Great. That means he’s stuck here in this unfamiliar world with this weird version of his brother-

“heh, well, you aren’t getting back home in that.”

Sans flinches and turns.  Papyrus is standing behind him, with his brother fast asleep in his arms.  Sans takes a big step back.  Even though he seems to be placated, Sans is still ill at ease with his brother’s counterpart being so close.

“yeah, no shit.” Sans snips, eyes glancing back to the machine.

“if you want you can come stay with us.” Papyrus says.

Sans thinks for a moment.  He knows he doesn’t have much of a choice.  He can either accept their hospitality or starve on the cold streets of Snowdin until some monster comes and finishes him off.

"are you sure?" Sans asks, still skeptical.

Papyrus shrugs.   “i still have questions about what happened.  'sides, it’s the least we could do for you after all you’ve done for us, ya know." 

Still, Sans isn’t all that comfortable with the idea of staying with an unfamiliar person for an indefinite period of time - especially another universe’s Papyrus.  Though, admittedly, they aren’t much alike.  This Papyrus, while he has the same voice as his brother, is much more soft spoken and lacks power behind his words.  He acts far more like how Sans would if he was given the freedom to do as he pleases.

Sensing his discomfort, Papyrus speaks up, “it won’t be forever.  we’ll find a way to repair one of our machines and get you home.”

Sans raises an eyebrow ridge, “one of your machines?”

Papyrus nods, “you aren’t the only one in the multiverse searching for ways of inter-dimensional travel.  i’m sure between the two of us we’ll find a way to replicate your method.” Papyrus gives a little wink and readjust his hold on Blue.  “so, you comin’ with us?”

Shrugging, Sans gives a reply.  “sure, i’ll crash with ya.”

Papyrus smirks and turns around.  Sans follows, hands deep in his pockets.  It's going to take a long time for him to get back to his universe, but hey, that's the risk of science.  He'll have a proper breakdown tomorrow, when he's less tired from being chased all around Snowdin.  

So, yawning, he lets this Papyrus lead the way back home.

**Notes for the Chapter:**

> The End.  
> OR IS IT!?  
> Nope! There are going to be a few more parts to this series, so subscribe to the Homeward series to be updated on those, or just check it really often, if that's how you do things. The next part to this will be up in about a week since I'm still working on it.
> 
> BONUS:  
> As I was doing the final edits on this, I realized that it would have been super cruel of me ending it with the machine being empty and Blue being missing god knows where, but the little marshmallow has suffered enough, don't you think?  
>  ~~heck no if I had thought if it earlier that is totally how I would have written it what are you talking about?~~
> 
> Well, if you stay for the next part, GREAT! If not, thanks for reading!!!


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